1. Field of Invention
The present invention relates to an exhaust brake, and more particularly, to an exhaust brake capable of maximizing assist brake performance without affecting an engine by keeping a predetermined back pressure even in a high speed section and a middle-low speed section without a loss in the back pressure by applying a check valve to a back pressure forming part so as to satisfy an engine allowable back pressure.
2. Description of Related Art
An exhaust brake is an apparatus which forms a back pressure at an engine exhaust side and applies a load to the engine so that a brake is caught.
FIG. 1 is a perspective view illustrating an exhaust brake according to the related art. As illustrated in FIG. 1, an exhaust pipe 10 is equipped with a butterfly 20, in which the butterfly 20 rotates based on a rotating shaft 22 to stop or open the exhaust pipe. The rotating shaft of the butterfly rotates by a force which allows a cylinder 30 mounted outside the exhaust pipe to push a rod 32. When the butterfly 20 stops the exhaust pipe 10, the back pressure rises. In this case, the back pressure applies a load to the engine so that the brake is caught.
Meanwhile, the butterfly 20 according to the related art is equipped with a hole 24 to satisfy an engine allowable back pressure. However, since the hole 24 permits a flow of air at all times, the back pressure may not formed properly in a middle-low speed section, such that brake performance may be suddenly degraded. Further, when a size of the hole is small to prevent the brake performance from degrading, the large back pressure is generated in a high speed section and thus exceeds the allowable back pressure, such that a cylinder head of an engine may be damaged.
As such, the exhaust brake structure according to the related art which does not properly exert the brake performance in the middle-low speed section is not suited to a current development trend or direction in automobile industry which seeks to downsize the engine.
Meanwhile, the butterfly 20 is opened and closed by the cylinder 30. Due to the structure of the butterfly 20, a gap between the butterfly 20 and an inner diameter portion of the exhaust pipe 10 cannot but be formed at both ends of the rotating shaft 22, such that air tightness may be reduced and the brake performance may be reduced.
Further, when the cylinder is operated to open and close the butterfly, a force which allows the butterfly to be pulled to the cylinder is applied in a shaft direction of the rotating shaft 22 and thus the butterfly is jammed into the exhaust pipe 10, such that an operation defect that the butterfly is not opened and closed properly may occur.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.